Key switch with axially misaligned shuttle bridging member



Jilly 1970 H. A. WOOLDRIDGE ETAL 3,

KEY SWITCH WITH AXIALLY MISALIGNED SHUTTLE BRIDGING MEMBER Filed May 15. 1968 Aw if SEQ 55% I um N HAROLD A'.WOOLDRIDGE KENNETH H.STEWARD w W UM/EMA? ATTORN INVENTORS.

United States Patent 3,521,015 KEY SWITCH WITH AXIALLY MISALIGNED SHUTTLE BRIDGING MEMBER Harold A. Wooldridge, Richmond, and Kenneth H. Steward, San Lorenzo, Califi, assignors to The Singer Company, a corporation of New Jersey Filed May 13, 1968, Ser. No. 728,678 Int. Cl. H01h 13/52, /18

US. Cl. 200159 4 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION The trend today is toward high-speed printers and more compact computer systems. In such devices, the keyboard is an important functional unit, the keys of the keyboard must be adaptable to high speed operation for the rapid selection of values or other characters to be printed or otherwise utilized in the system. In the past, a series of switches, such as leaf switches or microswitches, have been installed in the keyboard unit for control by the respective keys. A compact spacing and/ or arrangement of the keys being determined by the suitable placement of the switches. Because of the depth requirement for keys and switches and the necessarily wide spacing between keys, the spatial requirements for the keyboard unit becomes restrictive.

In Pat. No. 3,366,808, for Steward, issued Jan. 30, 1968, and assigned to the assignee of the present application, there is described a keyboard key having a unitized construction, i.e., the key and switch are combined in a housing. However, the structure is relatively complex and expensive to manufacture. Because of its complexity, a casing, or housing of considerable size must be employed and, due to this fact, the key does not readily lead itself to a compact grouping or arrangement of a plurality of such keys. The Steward key structure does have an advantage over prior devices for creating a voltage pulse by the impact of a hammer with a cantilevered crystal section. All of the parts, except for the key, being totally enclosed.

SUMMARY OF THE INVENTION The present invention constitutes an improvement over the Steward key structure as disclosed in Pat. No. 3,366,- 808 and relates particularly to a self-contained key-switch combination of simple and inexpensive construction.

The present invention provides a compact key module affording considerable flexibility in various keyboard arrangements for operator convenience. By virtue of a shortened stroke and lighter pressure requirement, the key is readily adaptable to easier and faster control by an operator with the closure of the switch contacts being independent of operator touch.

DESCRIPTION OF DRAWINGS FIG. 1 is a cross-sectional elevational view of the key module, and

FIG. 2 is a view similar to FIG. 1, showing the key fully depressed.

Referring to FIG. 1, a key guide member 10 is cylindrical in shape and is hollow, preferably molded, or formed, of a thermoplastic material. Integrally formed, internally of the guide member 10, and intermediate its ends, is a transverse wall 11 having an annular groove 12 formed in the top surface thereof. The larger diameter of the groove 12 is identical to the inside diameter of the upper portion of the cylindrical guide 10, while the smaller diameter is such that the width of the groove 12 is suflicient to accommodate a compression spring 13 seating on the bottom surface of the groove. Concentric with the upper portion of the cylindrical guide 10 is a bore 14 formed in the internal wall 11 for a purpose to be hereinafter described.

Adjacent its lower end, the guide member 10 is pro vided with an annular collar 15,, integrally formed therewith and effective to support the cylindrical guide on a keyboard mounting plate 16. The mounting plate 16 may serve to support a plurality of such guide members 10. In the lower end portion of the guide member 10 a series of female threads 20 are formed and are adapted for threaded engagement by the male thread portion 21 of a base member 22. Upon inserting the lower end portion of the guide member 10 in a suitable aperture in mounting plate 16 and threading the base member 22 into the guide 10, an annular flange 23 of the base 22 serves to secure the guide 10 in place on plate 16.

Base member 22 is counterbored to a depth approximately one-half its thickness with the remaining solid portion 24 thereof having a pair of identical diametrically-opposed holes 25 drilled or otherwise formed therein. Each of a pair of spring contacts 26 of a suitable electrically conductive material, such as beryllium copper, is suitably supported within the respective holes, or apertures, 25 by means of an insulating material preferably neoprene rubber, which is bonded or otherwise secured to the contacts 26 and to the walls of the respective holes 25. While the lower end portion of each of the contacts 26 extends below the base 22 sufficiently to permit the coupling of the electrical conducting leads 27 and 28, the upper end portion is formed angularly inwardly, each toward the other. At its upper extremity, each of the contacts 26 is arcuately formed as at 29. The arcuately formed ends 29 are in opposition, one to the other, and in spacedapart relationship to permit the entry of a bridging member therebetween to effect the flow of current across the electrical leads 27 and 28.

A key 33 is substantially cylindrical in configuration, preferably molded or formed of a thermoplastic material and comprising an outer cylindrical shell 35, as well as an inner cylindrical shell 36, integrally formed at their upper end with a closed end portion 37, which provides the operator touch surface for controlling the depression of the key. As the key 33 is depressed, it is guided in its movement by the engagement of the upper cylindrical portion of the guide member 10 in an annular channel 38 formed between the wall of the outer shell 35 and that of the concentric inner shell 36. Normally, compression spring 13 serves to resiliently maintain the key 33 in the upper or nondepressed position shown in FIG. 1, the lower end of the spring 13 being seated in the annular groove 12 in the transverse wall 11 and its upper end urged against the lower edge of the inner shell 36.

The extent of the upward travel of the key 33, under the influence of spring 13, is determined by a spring clip, generally indicated at 39, and comprising a ring 40 and a pair of vertically disposed spring clips 41. Ring 40 is secured in place between the collar 15 and mounting plate 16 by means of the flanged base 22. Formed upwardly from the outer peripheral edge of, and at right angles to, the ring 40 are the two diametrically opposed clips 41. At its upper free end, each clip 41 extends laterally inwardly and angularly upwardly providing a shoulder 42 engageable by an annular flange 43 formed at the ward movement of the key 33.

As the key 33 is depressed, a shutt e, generally indicated at 34, is urged into axial alignment with the bore 14 in the wall 11 of guide member for immediate engagement thereafter with contacts 26. Normally, the shuttle 34, which may be formed of an electrically conductive material, such as brass, is at rest in a position such that the axis of the shuttle is angularly disposed to the axis of the guide member 10 and bore 14 as seen in FIG. 1. However, upon depression of the key 33 by a finger pressure approximating four ounces, the shuttle 34 is moved to a position axially coincident with the axis of the guide member 10. Immediately thereafter, the shuttle moves downwardly to engage between the ends of the respective electrical contacts 26 (FIG. 2). To this end, the main body portion 48 of the shuttle 34 is cylindrical in form, having a diameter slightly less than that of the bore 14 in guide member 10. Coaxial with the main body portion 48 is a tapered spindle 49 which is integrally formed at its larger end with the convex base 50 of the main body 48. Extending upwardly of the main body 48 is a conoidal top section 51 connected coaxially by means of a stub shaft 52 with a disk or head 53 having a diameter greater than that of the main body 48 of the shuttle 34. It will be noted that although the shuttle 34 is preferably formed, in its entirety, of an electrically conductive material, it may, if deemed desirable, be formed or molded of a thermoplastic material with the spindle 49 only formed of brass or other conductive material.

Normally, the lower surface of the disk 53, adjacent the peripheral edge thereof, rests on the elliptical surface 54, formed by the inclined plane of a cylindrical stop sleeve 55 press fitted into a counterbore in the open end of the inner shell 36. The engagement of the head 53 of the shuttle 34 with the surface 54 ofsleeve 55 is resiliently maintained by a compression conical spring '56. The upper, or larger, end of spring 56 is disposed in an indented seat in the inner surface of the closed end portion 37 of.

key 33 coaxial with bore 14, while the smaller end of the spring is seated in a concentric recess in the disk 53 of shuttle 34.

In the normal, or nondepressed, position of the key 33, an angular portion of the convex surface 50 of the shuttle 34 is disposed adjacent a corresponding portion of a chamfer, or bevelled edge, 60 of the 'bore 14. Upon the application of approximately a four-ounce operator load on the key 33, and following approximately a .032 of an inch of travel, the bevelled edge 61 of sleeve 55 contacts the surface of the conoidal section 51 of shuttle 34. During the succeeding .053 of an inch of travel of the key, the shuttle 34 is cammed 01f of the chamfer 60 into axial alignment with the bore 14. As the key 33 travels this initial .085 of an inch, approximately, the inclined plane surface 54 of sleeve 55 moves out of engagement with the disk 53 of the shuttle. At this same time, the conical spring 56 is further compressed so that, upon axial alignment of the shuttle 34 with the bore 14, the shuttle is triggered and, under the influence of compressed spring 56, is immediately urged downwardly to engage the spindle 49 between the arcuately-formed ends 29 of contacts 26, as seen in FIG. 2. As the engagement of the spindle 49 with the contacts 26 is effected, the depression of the key 33 is completed for a full travel of approximately- .125 of an inch. Thus, current flow is effected across leads 27 and 28 for the control of associated equipment or circuitry.

What is claimed is:

1. A keyboard key assembly comprising:

a guide cylinder adapted to be supported in a keyboard and including a transverse wall having a coaxial bore therein,

a base element removably mounted on said guide cylinder for retaining said guide cylinder in said keyboard,

a pair of electrical conductors supported in spaced apart relationship in said base element,

a manually operable keyslidably supported on said guide cylinder for movement from a normally inoperative to an operative position,

a resilient means biasing said key to the inoperative position,

a contact means normally inactively supported within said key for movement to an active position relative to the bore in said transverse wall of said guide. cylinder upon the initial depression of said key for engagement thereafter between said electrical conductors,

a cylindrical support member movable with said key normally yieldably supporting said contact means in axial misalignment with the bore in said transverse wall of said guide cylinder and operable upon initial movement of said key to move said contact means into active position for passage within said bore, and

a conical compression spring normally biasing said contact means into engagement with said cylindrical support member and compressible by said key, during the initial'portion of the depression of the key and the movement of said contact means to active position, to immediately thereafter effect passage of said contact means through said bore and into engagement between said electrical conductors.

2. A key assembly of the character described in claim 1 wherein said contact means comprises a shuttle having a cylindrical main body element for movement axially in said bore,

an electrically conductive tapered spindle carried by said main body element for engagement between said electrical conductors,

a disk normally maintained in engagement with said support member by said conical spring, and

a conoidal section connecting said disk with said main body element whereby said main body element is resiliently maintained out of axial alignment with the bore in said transverse wall.

3. A key assembly of the character described in claim 2 wherein said support member comprises a hollow cylinder carried by said key coaxial with said bore having the top surface disposed in an inclined plane for engagement by said disk under the influence of said conical spring and the lower inner edge bevelled to engage the inclined surface of said conoidal section to cam said main body element into axial alignment with said bore during the initial depression of said key.

4. A key assembly of the character described in claim 3 wherein said conical spring is disposed between said key and said disk and is compressed during the initial depression of said key to cam said main body element into axial alignment with said bore and is thereafter elfective to actuate said main body element to cause said spindle to complete a current flow across said conductors.

References Cited UNITED STATES PATENTS 2,386,162 10/ 1945 Hetherington 200-77 2,748,216 5/1956 Schneider et al. 200-77 2,881,292 4/1959 Winter et al.

3,045,082 7/1962 Mason 200-68 3,244,847 4/1966 Erpel 200-159 FOREIGN PATENTS 557,980 8/1932 Germany.

ROBERT K. SCHAEFER, Primary Examiner R. A. VANDERHYE, Assistant Examiner US. Cl. X.R. 200-77 

